JSON Commands Cheat Sheet

Tags

Quick reference JSON commands you should know.

JavaScript Basics
Examples

{
  "name": "Jason",
  "age": 39,
  "height": 1.92,
  "gender": "M",
  "salary": 70000,
  "married": true,
  "children": [
    {"name": "Tom", "age": 9, "gender":"M"},
    {"name": "Ava", "age": 7, "gender":"F"}
  ]
}
Types
Number
Double precision floating-point
String
Series of characters
Boolean
true or false
Array
Ordered sequence of values
Value
String, Number, Boolean, null etc
Object
Unordered collection of key/value pairs
null
Null or Empty
Objects

{
  "color": "Purple",
  "id": "210",
  "composition": {
    "R": 70,
    "G": 39,
    "B": 89
  },
  "empty_object": {}
}
 
Multiple key/value pairs separated by a comma
2D Array

{
  "my_sequences": [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9, 0],
    [10, 11]
  ]
}
                    
Nested

{
  "Jack": {
    "id": 1,
    "name": "Franc",
    "salary": 25000,
    "hobby": ["a", "b"],
    "location": {
        "country": "A", "city": "A-A"
    }
  }
}
                    
String
\"
Double quote
\\
Backslash
\/
Forward slash
\b
Backspace
\f
Form feed
\n
Newline
\r
Carriage return
\t
Tab
\u
Trailed by four hex digits
Number
Integer
Digits 1-9, 0 and positive or negative
Fraction
Fractions like 0.3, 3.9
Exponent
Exponent like e, e+, e-, E, E+, E
Arrays

[1, 2, 3, 4, 5]
                    
Begins with [ and ends with ]
Array of objects

 {
  "children": [
    {"name": "Jimmy Smith", "age": 15},
    {"name": "Sammy Sosa", "age": 12}
  ]
}
                    
Object of arrays

{
  "attributes": ["a1", "a2"],
  "methods": ["getter", "setter"],
  "empty_array": []
}
                    
Object of objects

{
  "Mark McGwire": {
    "hr": 65,
    "avg": 0.278
  },
  "Sammy Sosa": {
    "hr": 63,
    "avg": 0.288
  }
}
                    
Access JSON in JavaScript
Access Objects

let myObject = {
  "name": "Jason",
  "last": "Doe",
  "age": 39,
  "gender": "M",
  "salary": 70000,
  "married": true
};
                
myObject.name
"Jason"
myObject["name"]
"Jason"
myObject.age
39
myObject.other
undefined
myObject.[0]
undefined
Access Array of Objects

let myArray = [
  {
    "name": "Jason",
    "last": "Doe",
    "age": 39,
    "gender": "M",
    "salary": 70000,
    "married": true
  },
  {
    "name": "Tom",
    "last": "Smith",
    "age": 42,
    "gender": "F",
    "salary": 80000,
    "married": true
  },
  {
    "name": "Amy",
    "last": "Burnquist",
    "age": 29,
    "gender": "F",
    "salary": 60000,
    "married": false
  }
];
                
myArray[0]
{"name": "Jason", ...}
myArray[1].name
"Tom"
myArray[1][2]
42
myArray[3]
undefined
myArray[3].gender
TypeError: Cannot read...
Access Array

let myArray = [
  "Jason",
  "Doe",
  39,
  "M",
  70000,
  true
];
                
myArray[1]
"Doe"
myArray[5]
true
myArray[6]
undefined
Access Nested

let myObject = {
  "ref": {
    "name": 0,
    "last": 1,
    "age": 2,
    "gender": 3,
    "salary": 4,
    "married": 5
  },
  "jdoe": [
    "Jason",
    "Doe",
    39,
    "M",
    70000,
    true
  ],
  "jsmith": [
    "Tom",
    "Smith",
    42,
    "F",
    80000,
    true
  ]
};
                
myObject.ref.age
2
myObject["ref"]["age"]
2
myObject.jdoe
["Jason", "Doe", 39 ...]
myObject.jsmith[3]
"F"
myObject[1]
undefined
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